#include <stdio.h>
int main()
{
    FILE* fp=fopen("log.txt","a");
    if(fp==NULL)
    {
        perror("fopen");
        return 1;
    }

    fprintf(fp,"helloworld,%d,%s,%lf\n",10,"whb",3.14);
    fclose(fp);

    return 0;
}
